I looked at that link - but if I read it correctly it's a one-at-a-time kind of operation.

Indeed, it is.

I have thousands of messages, many with attachments that I want to move so I don't think it's going to work for me.

That's quite a lot.

I think I may have found the solution to your problem, although not yet tested by myself.

Since all your emails are stored in an MBX file, it should be quite easy to rename the previous attachment directory to the current one.Use a text editor (I do use EditPlus) and open the MBX file.Now do a Search and Replace. Save afterwards again as MBX.

Just make sure Poco is closed and before you run it life, do it first with a test MBX file.Just copy an existing MBX file and name it test.mbx.When all renaming has been done, re-open Poco so that MBX file can be reindexed.Do those attachments show now

If they do, make a backup first, but before you do close Poco again and delete test.mbx.

Now when the backup is done, go further with opening each MBX file which does have that problem.

Once all is done, delete all IDB files, so Poco can reindex them once started.

Just a suggestion how to do it quicker. Still a lot of work, but less then with the script.

I don't come here very often (only when I have a problem) but whenever I do you seem to be here to hold my hand.

I do help whenever I can.
It's my pleasure to help to anyone.
Must be a coincidence I guess.